Networks in which the network elements communicate with one another by means of packet switching are used for transmission of data and for communication purposes. Networks such as these may either be locally bounded, in which case they are referred to as LANs (LAN=Local Area Network), or else they may be distributed worldwide (WAN=Wide Area Network), for example the Internet. In addition to the connecting paths (data line), networks such as these comprise a large number of different network elements, such as switches, routers and computers (servers, workstations), the latter with applications installed in them.
For communication between the network elements, it is generally irrelevant where these network elements are physically and geographically arranged.
The data is in each case combined to form data packets for transport, and is addressed using a unique network address for the receiving network elements. Since the onward transport of the data in the network is carried out in an automated manner, the actual location of the addressed network component, for example a server with an application, is irrelevant to the user. However, this situation is different when network elements have to be accessed for the purpose of monitoring or for maintenance purposes. Control procedures are often required for this purpose, and these have to be carried out directly at the relevant network element.
In packet-switching networks, it is important to identify in good time whether an application or a network element is operating correctly, is faulty or has even stopped prematurely (“been terminated”). It should be also possible to monitor this from a central, remote location (workstation). In order to make it possible to monitor and control the network elements of widely distributed networks from a central location, these network elements frequently have interfaces for remote access. These interfaces generally operate using a standardized protocol in order that various network elements and applications can be administered from a central point owing to a single application program, which is also referred to as an administration tool. One such standardized protocol is, for example, the SNMP (Simple Network Management Protocol), which allows simultaneous monitoring and control of widely differing network elements and applications within one administration tool. The administration tool is, for example, a Presence Application, which is installed on a PC and is also referred to as an NMS (Network Management Station).
The individual applications (processes) and network elements are monitored and controlled for remote access by local monitoring instants, so-called management clients. Each management client for a network element or for an application is connected to an instant which combines the state messages from the management client and converts them to a message in accordance with the protocol. This instant is also often referred to as an SNMP agent, and the messages are frequently referred to in the literature as “SNMP traps”, or “traps”, for short. The SNMP agent sends the traps to one or more network management stations, where the monitored network elements and applications and their current states (for example online, offline, or the instantaneous load level) are displayed (indicated), and from where control commands can be transmitted back to the network elements and applications.
The control commands and the state information, that is to say the traps, are in this case transmitted as UDP messages (UDP=User Datagram Protocol).
In modern data networks, in particular in relatively large company networks and in the Internet, communication methods are frequently used and are known as presence/instant messaging methods. The examples of this are the applications “Windows Messenger”, “AOL Messenger” or “ICQ”. In this case, specific applications are installed on the workstation computers of the users, which are frequently also referred to as messaging applications and in which a list with preferred communication partners in the network is maintained. Lists such as these are also referred to as “buddy lists”, because this communication method is preferably used simply for interchanging text messages with friends and acquaintances (so-called “chatting”). In the buddy list, symbols, for example in the form of a red or a green dot, mark the current status of the possible communication partner, that is to say for example whether the relevant user is currently accessible (Online), is busy, or is not registered with the network (Offline).
With regard to presence/instant messaging applications, a distinction is drawn between those with a central server, and those without a central server. While, in the case of the arrangements without a central server, the messages relating to the current state of the individual users and the messages relating to the state changes, for example offline to online, must be interchanged directly between all the relevant workstation computers, in the case of those arrangements with central servers a list of all the communication partners which can be accessed in the communication network is maintained in these servers. The state information on the individual users and the messages relating to the state changes are just transmitted from the individual workstations to these central servers, and are then noted in its list. For each communication partner in this list, note is made relating to the workstation computers on the network at which this communication partner is located in the buddy list. State messages and messages relating to state changes are then sent from this server only to those workstation computers whose user relates to this communication partner. As soon as one of the communication partners is identified in the buddy list as being online, it is possible, for example, to simply interchange text messages with that communication partner. This procedure is commonly referred to as “chatting”.
Presence/instant messaging applications are known in various networks with different protocols. The Session Initiating Protocol (SIP) is predominantly used for setting up multimedia sessions in data networks, for example for speech transmission (“Voice-over-IP”=speech transmission with the aid of the Internet Protocol); in this context, the SIMPLE extension (SIMPLE=SIP for Instant Messaging and Presence Leveraging Extensions) defines a protocol extension which can be used for the purpose of presence/instant messaging.
One known method for monitoring and, in particular also for controlling computer-supported applications from a remote location is the use of so-called PC remote control programs. One example of a program such as this is the PC-Anywhere software manufactured by Symantec. In this case, special software is installed both on the PC to be monitored and to be controlled and on the PC which is used for maintenance purposes, allowing the remotely located PC to be controlled by mouse/keyboard inputs, and its screen content to be displayed on the PC's own screen. However, this is dependent on a compatible operating system being installed on both PCs and on a data channel with sufficient bandwidth being connected between the two components.
One disadvantage that has been found with the known methods for monitoring applications is that the applications and processes to be monitored must be configured in a predetermined manner. In addition, special, proprietary software (for example “HP OpenView”) must often be installed in the PC hardware that is used for monitoring.
Proprietary supplements are additionally required for remotely controlled administration using the SNMP method, for example the use of programs for remote control PCs, for example “PC-Anywhere”. Applications are monitored by means of the SNMP protocol in conjunction with the connection less UDP protocol, so that the loss of an event message (“Trap”) is not always recorded.